Main Engine Cut Off

T+72: SpaceX’s Motivation for Falcon Heavy

SpaceX launched Falcon Heavy last week and shook up the space launch world. I spend some time thinking through SpaceX’s motivations for building Falcon Heavy, and what its effects might be on the world around it.

This episode of Main Engine Cut Off is brought to you by 27 executive producers—Kris, Pat, Matt, Jorge, Brad, Ryan, Jamison, Nadim, Peter, Donald, Lee, Jasper, Chris, Warren, Bob, Brian, Russell, John, Moritz, Tyler, Laszlo, and six anonymous—and 125 other supporters on Patreon.

Thanks to January Patrons

Very special thanks to the 144 of you out there supporting Main Engine Cut Off on Patreon for the month of January. Your support keeps this blog and podcast going, and most importantly, it keeps it independent.

And a huge thanks to the 24 executive producers of Main Engine Cut Off: Kris, Pat, Matt, Jorge, Brad, Ryan, Jamison, Nadim, Peter, Donald, Lee, Jasper, Chris, Warren, Bob, Brian, Russell, John, Moritz, and five anonymous executive producers. I could not do this without your support, and I am extremely grateful for it.

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T+71: Commercial Crew, Congress, and the GAO

The Commercial Crew program—NASA, SpaceX, Boeing, and more—went in front of Congress to discuss the current status of the crew launch systems in development. Concurrently, the GAO released a report warning that more delays are likely, and could put NASA in a tough spot. I share some thoughts on the matter and talk through what is likely to happen this year.

This episode of Main Engine Cut Off is brought to you by 24 executive producers—Kris, Pat, Matt, Jorge, Brad, Ryan, Jamison, Nadim, Peter, Donald, Lee, Jasper, Chris, Warren, Bob, Brian, Russell, John, Moritz, and five anonymous—and 120 other supporters on Patreon.

NASA’s Launch Vehicle “Stable Configuration” Double Standard

This issue cropped up yet again in the Commercial Crew hearing in the House yesterday (at the 1 hour, 7 minute, 5 second mark):

Space Subcommittee Chairman Brian Babin (R-Texas): Dr. Sanders, how many launches with a stable configuration should NASA require SpaceX and Boeing to achieve before certification?

Dr. Patricia Sanders, chair, NASA Aerospace Safety Advisory Panel: That’s a very difficult question, thank you. Right now, I believe NASA is planning to require seven launches with that configuration, and we believe that’s an appropriate number. There’s some statistical evidence—that Mr. Gerstenmaier could probably talk to a little bit better than I can—why that is a reasonable number. It is not a totally random number, it is a number that’s predicated on having more than a few, but having a timeframe in which you can actually accomplish those and still get on with certification and make the right risk decision on flying.

This requirement grew out of concerns about SpaceX and how frequently they update the design of Falcon 9. And from where NASA stands, it’s a totally valid concern and requirement.

The problem is that it has very blatantly only ever been applied to SpaceX.

Starliner is flying on top of an Atlas V—a launch vehicle with a long, successful history. But flying crew on an Atlas V requires some changes to eliminate abort black zones—sections of flight where aborts are impossible. And doing that requires adding a second engine to Centaur, the upper stage of the Atlas V.

Dual Engine Centaur is not a new concept—Centaur flew with two engines for most of its history. But the last flight of a Dual Engine Centaur was on February 21, 2002–an Atlas IIIB launching Echostar 7. That launch was the first flight of Common Centaur, which is the version of Centaur flying today on Atlas V.

Now, I’m sure there have been design changes to Centaur in the last 16 years, but let’s say that the Echostar 7 launch counts as Dual Engine Common Centaur’s first flight. Then we have to figure out what NASA constitutes a stable configuration: is it a particular variant of a fully-integrated stack, or can first and second stages be flown independently and count towards the stable configuration flight count? From what I’ve gathered, it’s the former.

Starliner’s first flight will be the first flight of the Dual Engine Common Centaur on Atlas V. Starliner’s second flight—its first with crew—will be flying the second.

Two is a long way from seven.

Stacking Mission Extension Vehicles

Really interesting technical note on how Orbital ATK’s Mission Extension Vehicles stack with other satellites in an article by Caleb Henry of SpaceNews:

Intelsat is not the first satellite operator to agree to launch an Orbital ATK-built satellite stacked with the company’s Mission Extension Vehicle. Late this year, the Eutelsat 5 West B satellite will be stacked with MEV-1 for launch aboard an International Launch Services Proton rocket. Both Galaxy-30 and Eutelsat 5 West B are based on Orbital ATK’s GEOStar spacecraft platform.

The ability to directly stack MEVs with GEOStar satellites gives Orbital ATK a new selling point. Because one side of the MEV is devoid of crushable instruments, a satellite can be stacked on top of it without using the protective barrier Ariane 5 normally places between dual-launched satellites. Stacking MEV with a GEOStar satellite enables dual launch on rockets that have no divider, like Proton, or, in the case of MEV-2, enable a third passenger to share the cost of a launch.

T+70: Polar Launches from Cape Canaveral

The US Air Force has developed a viable corridor for launching to polar and other high-inclination orbits from Cape Canaveral. I spend some time thinking through who may be interested in using that corridor and what its existence could mean for the newer launch vehicles in development.

This episode of Main Engine Cut Off is brought to you by 24 executive producers—Kris, Mike, Pat, Matt, Jorge, Brad, Ryan, Jamison, Nadim, Peter, Donald, Lee, Jasper, Chris, Warren, Bob, Brian, Russell, John, and five anonymous—and 113 other supporters on Patreon.

Polar XS-1 Launches

In thinking through who may launch to high-inclination orbits from the Cape, I totally forgot about DARPA’s XS-1 that will be based out of Cape Canaveral. I would be surprised if there weren’t plans to launch XS-1 from Vandenberg, but as of yet, we haven’t heard anything. Maybe the Department of Defense had XS-1 in mind when developing a polar corridor from Cape Canaveral?

The trouble there is that XS-1’s payload to orbit is already fairly low—1,360 kilograms—and launching to polar orbits from the Cape will lower that even more. That said, a few hundred kilograms to high inclinations would be competitive with Electron or LauncherOne-class vehicles.

Mars’ Seasonal Methane Cycles

Fascinating piece by Eric Hand, for Science:

In the southern winter, some of that CO2 freezes out onto the large southern polar cap, making the overall atmosphere thinner. That boosts the concentration of any residual methane, which doesn’t freeze, and by the end of northern summer this methane-enriched air makes its way north to Curiosity’s location, Forget says. Seasonal variations in dust storms and levels of UV light could also affect the abundance of methane, if interplanetary dust is its primary source.

But, Webster said at the meeting, the seasonal signal is some three times larger than those mechanisms could explain. Maybe the methane—whatever its source—is absorbed and released from pores in surface rocks at rates that depend on temperature, he said. Another explanation, “one that no one talks about but is in the back of everyone's mind,” is biological activity, says Mike Mumma, a planetary scientist at Goddard Space Flight Center in Greenbelt, Maryland. “You’d expect life to be seasonal.”

Another hypothesis, which has an opportunity to be tested in just a few weeks:

Other scientists are looking skyward. Marc Fries, the cosmic dust curator at Johnson Space Center in Houston, Texas, says the source of methane spikes could be the hail of tiny meteors that falls when a planet crosses a comet’s orbit and sweeps up carbon-rich dust and debris shed by the comet. Fries says that as the dust particles vaporize at altitudes of tens of kilometers, the same chemical reaction that produces methane from interplanetary dust at the surface would take place more quickly, driven by the stronger UV light at high altitudes. All the claimed methane spikes over the past 2 decades occurred within about 2 weeks of a known martian meteor shower, Fries and his colleagues found. “It could be a cause, and it could be a coincidence,” he says.

It happens that Fries will have a chance to test the hypothesis. On 24 January, Mars will have a close brush—less than a tenth of the Earth-moon distance—with the orbit of comet C/2007 H2 Skiff. Mumma is skeptical about Fries’s idea, but he will nevertheless be watching for methane with his telescope in Hawaii in the days after the encounter. The MAVEN and Curiosity teams also plan to watch. “This is a great opportunity to test this hypothesis,” Crismani says.